To their adoring fans, Lucille Ball and Desi Arnaz were the loving couple they portrayed on TV — but their real-life marriage was a living hell! “Desi was always adorable, handsome, romantic…but he cheated, he drank and he gambled,” said a longtime Hollywood insider. “Lucy had to lie, pretend and put on a good face because they were working together and had commitments!”

And behind closed doors, Desi’s compulsive womanizing and boozing led to explosive fights and violent outbursts that ripped their tempestuous marriage apart. The couple's brutal battles reached their peak while “I Love Lucy” was on the air from 1951 to 1957, but things were never peaceful between the passionate power couple!

They were married in 1940, with Lucy first filed for divorce just two days before their fourth wedding anniversary. Her official complaint charged “extreme mental cruelty.” But a day after the divorce was granted, they reconciled. That would be the first of many times that the zany redhead forgave her wayward husband and took him back.

After the births of their children — Lucie in 1951 and Desi Jr. 18 months later — Lucy’s happiness was complete. Desi, however, was soon back to his philandering ways. His cheating made humiliating headline news in 1954, as published reports caught him out with “cuddle-for-cash babes.”

“Desi would take five or six girls back to his hotel suite and make them nice and cozy in the parlor before calling them into the bedroom one by one,” revealed an insider, while another source added: “Lucy was deeply hurt by Desi’s constant betrayals with other women — often prostitutes! Desi couldn’t understand why Lucy was so hurt. He’d ask, ‘What is she so excited about? They’re only hookers.’”

“During one argument,” recalled a longtime pal, “Lucy picked up a hammer and knocked Desi cold with a blow to the head. She was convinced she’d killed him, and started to concoct a story about how he’d fallen — but Desi came to. In another fight, as they entertained dinner guests, Desi hit Lucy in the face and split her lip. A friend of hers then smacked Desi over the head with a bottle.”

“Those last five years were sheer, unadulterated hell,” Lucy once confessed. “We both knew it was over, but we had commitments to fill so we stayed together. I was hoping in my heart a miracle might happen, but people don’t really change.”

The TV legend admitted that she didn’t cope well. “I stored up all the hurts and humiliations — not the hurts of a day or a week, but the hurts of years,” she said. “Then some little thing opens up the dam and all the resentment rushes out!”

The final breaking point came in November 1959, just days before their 19th wedding anniversary. Lucy and Desi were discussing production matters at the studio. Desi, as usual, drank too many daiquiris which she ignored until he belched loudly — not once but twice, recalled a source.

The insider recounted how — after screaming, "You bastard!" — Lucy picked up an empty cocktail glass and hurled it against the wall and stormed out. Desi chased after her and told her he wanted a divorce. “I can’t keep living this way,” he said. Lucy flew into a tantrum. “Then why don’t you die then?” she yelled. “You cheat! You drunken bum! By the time I get through with you, you’ll be as broke as when you left Cuba!”

But it didn’t turn out that way, said sources. TV’s favorite couple remained soul mates to the end. (They're seen together here in 1974.) Desi, in a note for the book “Desilu: The Story of Lucille Ball and Desi Arnaz,” even wrote: “Lucy was the show. Viv, Fred, and I were just props. Damn good props, but props nevertheless. P.S. ‘I Love Lucy’ was never just the title.”

Jack Carter, who was the best man when Lucy wed nightclub comic Gary Morton in 1961, added: “Lucy loved Desi till the day she died. He was the father of her kids. Even after she married Gary, she’d still run these lovely home movies of her and Desi and the kids when they were little.”

Not surprisingly, dying Desi’s final words in 1986 were said during a phone call to Lucy. His ex was about to attempt a comeback in the short-lived sitcom "Life With Lucy" before her own death in 1989. “I love you too, honey,” said Desi. “Good luck with your show.”